The present invention relates to a turbocharger system in an internal combustion engine, and, more particularly, to a turbocharger system including a plurality of turbines with individual variable nozzles.
An internal combustion engine may include one or more turbochargers for compressing a fluid which is supplied to one or more combustion chambers within corresponding combustion cylinders. Each turbocharger typically includes a turbine driven by exhaust gases of the engine and a compressor which is driven by the turbine. The compressor receives the fluid to be compressed and supplies the fluid to the combustion chamber. The fluid which is compressed by the compressor may be in the form of combustion air or a fuel and air mixture.
It is known to detect a difference in output between multiple turbochargers in a turbocharger system to determine whether a failure has occurred. For example, U.S. Pat. No. 5,845,495 (Schray et al.) discloses a turbocharger system with each turbocharger having a turbine and single compressor wheel. If a speed deviation above a threshold level occurs between the turbochargers, corrective actions may be taken to prevent damage to one or more of the turbochargers. Such a system is effective to prevent damage to the individual turbochargers, but fails to provide optimum output performance from the turbocharger system.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the invention, a turbocharger system for an internal combustion engine is provided with a plurality of turbochargers. Each turbocharger includes a rotatable shaft; a turbine having a turbine wheel carried by the shaft, an inlet and a variable nozzle at the inlet; and a multi-stage compressor. The multi-stage compressor includes a first compressor wheel carried by the shaft, an axially extending first inlet associated with the first compressor wheel, a radially extending first outlet associated with the first compressor wheel, a second compressor wheel carried by the shaft, an axially extending second inlet associated with the second compressor wheel, a radially extending second outlet associated with the second compressor wheel, and an interstage duct fluidly interconnecting in series the first outlet associated with the first compressor wheel with the second inlet associated with second compressor wheel. At least one sensor is provided, with each sensor being configured to sense an operating parameter associated with the turbocharger system and provide an output signal. A controller is coupled with each sensor and with each variable nozzle. The controller independently controls operation of each variable nozzle dependent upon at least one output signal.
In another aspect of the invention, a method of operating a turbocharger system in an internal combustion engine is provided with the steps of: providing a plurality of turbochargers, each turbocharger including a rotatable shaft; a turbine having a wheel carried by the shaft, an inlet and a variable nozzle at the inlet; and a multi-stage compressor including a first compressor wheel carried by the shaft, an axially extending first inlet associated with the first compressor wheel, a radially extending first outlet associated with the first compressor wheel, a second compressor wheel carried by the shaft, an axially extending second inlet associated with the second compressor wheel, a radially extending second outlet associated with the second compressor wheel, and an interstage duct fluidly interconnecting in series the first outlet of the first compressor wheel with the second inlet of the second compressor wheel; sensing at least one operating parameter associated with the turbocharger system using a sensor; and independently controlling operation of each variable nozzle using a controller, dependent upon the sensed operating parameter.